WASHINGTON  Hidden in the X-rated pictures on several
pornographic Web sites and the posted comments on sports chat rooms may lie
the encrypted blueprints of the next terrorist attack against the United States
or its allies. It sounds farfetched, but U.S. officials and experts say it's
the latest method of communication being used by Osama bin Laden and his associates
to outfox law enforcement. Bin Laden, indicted in the bombing in 1998 of two
U.S. embassies in East Africa, and others are hiding maps and photographs of
terrorist targets and posting instructions for terrorist activities on sports
chat rooms, pornographic bulletin boards and other Web sites, U.S. and foreign
officials say.

"Uncrackable encryption is allowing
terrorists  Hamas, Hezbollah, al-Qaida and others  to communicate
about their criminal intentions without fear of outside intrusion," FBI Director
Louis Freeh said last March during closed-door testimony on terrorism before
a Senate panel. "They're thwarting the efforts of law enforcement to detect,
prevent and investigate illegal activities."

A terrorist's tool

Once the exclusive domain of the National Security Agency,
the super-secret U.S. agency responsible for developing and cracking electronic
codes, encryption has become the everyday tool of Muslim extremists in Afghanistan,
Albania, Britain, Kashmir, Kosovo, the Philippines, Syria, the USA, the West
Bank and Gaza and Yemen, U.S. officials say.

It's become so fundamental to the operations of these groups
that bin Laden and other Muslim extremists are teaching it at their camps in
Afghanistan and Sudan, they add.

"There is a tendency out there to envision a stereotypical
Muslim fighter standing with an AK-47 in barren Afghanistan," says Ben Venzke,
director of special intelligence projects for iDEFENSE, a cyberintelligence
and risk management company based in Fairfax, Va.

"But Hamas, Hezbollah and bin Laden's groups have very
sophisticated, well-educated people. Their technical equipment is good, and
they have the bright, young minds to operate them," he said.

U.S. officials say bin Laden's organization, al-Qaida,
uses money from Muslim sympathizers to purchase computers from stores or by
mail. Bin Laden's followers download easy-to-use encryption programs from the
Web, officials say, and have used the programs to help plan or carry out three
of their most recent plots:

Wadih El Hage, one of the suspects in the 1998 bombing of two U.S. embassies
in East Africa, sent encrypted e-mails under various names, including "Norman"
and "Abdus Sabbur," to "associates in al Qaida," according to the Oct. 25,
1998, U.S. indictment against him. Hage went on trial Monday in federal court
in New York.

Khalil Deek, an alleged terrorist arrested in Pakistan in 1999, used encrypted
computer files to plot bombings in Jordan at the turn of the millennium, U.S.
officials say. Authorities found Deek's computer at his Peshawar, Pakistan,
home and flew it to the National Security Agency in Fort Meade, Md. Mathematicians,
using supercomputers, decoded the files, enabling the FBI to foil the plot.

Ramzi Yousef, the convicted mastermind of the World Trade Center bombing
in 1993, used encrypted files to hide details of a plot to destroy 11 U.S.
airliners. Philippines officials found the computer in Yousef's Manila apartment
in 1995. U.S. officials broke the encryption and foiled the plot. Two of the
files, FBI officials say, took more than a year to decrypt.

"All the Islamists and terrorist groups are now using the
Internet to spread their messages," says Reuven Paz, academic director of the
Institute for Counter-Terrorism, an independent Israeli think tank.

Messages in dots

U.S. officials and militant Muslim groups say terrorists
began using encryption  which scrambles data and then hides the data in
existing images  about five years ago.

But the groups recently increased its use after U.S. law
enforcement authorities revealed they were tapping bin Laden's satellite telephone
calls from his base in Afghanistan and tracking his activities.

"It's brilliant," says Ahmed Jabril, spokesman for the
militant group Hezbollah in London. "Now it's possible to send a verse from
the Koran, an appeal for charity and even a call for jihad and know it
will not be seen by anyone hostile to our faith, like the Americans."

Extremist groups are not only using encryption to disguise
their e-mails but their voices, too, Attorney General Janet Reno told a presidential
panel on terrorism last year, headed by former CIA director John Deutsch. Encryption
programs also can scramble telephone conversations when the phones are plugged
into a computer.

"In the future, we may tap a conversation in which the
terrorist discusses the location of a bomb soon to go off, but we will be unable
to prevent the terrorist act when we cannot understand the conversation," Reno
said.

Here's how it works: Each image, whether a picture or a
map, is created by a series of dots. Inside the dots are a string of letters
and numbers that computers read to create the image. A coded message or another
image can be hidden in those letters and numbers.

They're hidden using free encryption Internet programs
set up by privacy advocacy groups. The programs scramble the messages or pictures
into existing images. The images can only be unlocked using a "private key,"
or code, selected by the recipient, experts add. Otherwise, they're impossible
to see or read.

"You very well could have a photograph and image with the
time and information of an attack sitting on your computer, and you would never
know it," Venzke says. "It will look no different than a photograph exchanged
between two friends or family members."

Even if they find it, the encrypted message or image is
impossible to read without cracking the encryption's code. A senior Defense
Department mathematician says cracking a code often requires lots of time and
the use of a government supercomputer.

It's no wonder the FBI wants all encryption programs to
file what amounts to a "master key" with a federal authority that would allow
them, with a judge's permission, to decrypt a code in a case of national security.
But civil liberties groups, which offer encryption programs on the Web to further
privacy, have vowed to fight it.

Officials say the Internet has become the modern version
of the "dead drop," a slang term describing the location where Cold War-era
spies left maps, pictures and other information.

But unlike the "dead drop," the Internet, U.S. officials
say, is proving to be a much more secure way to conduct clandestine warfare.

"Who ever thought that sending encrypted streams of data
across the Internet could produce a map on the other end saying 'this is where
your target is' or 'here's how to kill them'?" says Paul Beaver, spokesman for
Jane's Defense Weekly in London, which reports on defense and cyberterrorism
issues. "And who ever thought it could be done with near perfect security? The
Internet has proven to be a boon for terrorists."